Java 更新对象级联关系复制子对象时的Spring数据

我正在使用带有jpa注释的Spring数据创建一个应用程序

我在问题和选择之间定义了一个多对多关系，所以我有一个问题选择对象来将多对多关系一分为二

我试图做到的是，当一个问题被保存时，所有相关的选择都会随问题一起保存/更新

这是我目前的代码：

@Entity
@Table(name = "question")
public class Question {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "ID")
    private long id;


    @OneToMany(fetch = FetchType.EAGER, mappedBy = "question",
         cascade={CascadeType.PERSIST, CascadeType.MERGE})
    private Set<QuestionChoice> questionChoices;
…
}

@Entity
@Table(name="question_choice")
public class QuestionChoice {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="id")
    private long id;

    @ManyToOne
    @JoinColumn(name="questionId", referencedColumnName="id")
    private Question question;

    @ManyToOne(cascade={CascadeType.PERSIST, CascadeType.MERGE})
    @JoinColumn(name="choiceId", referencedColumnName="id")
    private Choice choice;

     …
 }

@Entity
@Table(name = "CHOICE")
public class Choice {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "ID")
    private long id;


    @OneToMany(mappedBy = "choice")
    private List<QuestionChoice> questions;
 …

}

@Repository
public interface QuestionRepository extends JpaRepository<Question,Long> {

}

---

任何解释都将不胜感激。

try-testQuestion=dao.getQuestionRepo（）.save（testQuestion）；-该引用可能未被更新try-testQuestion=dao.getQuestionRepo（）.save（testQuestion）；-引用可能没有被更新

@Test 
public void TestSaveQuestionAndAddChoices(){
    Question testQuestion = new Question();
    testQuestion.setDescription("Test");
    testQuestion.setClarification("Test Clarification");
    testQuestion.setAnswerExplanation("Test Answer");
    testQuestion.setLinkForAdditionalInformation("https://link5.com");
    testQuestion.setPoints(7);
    testQuestion.setTimeToAnswer(100);

    /** Check if the Question Id is correct Changed by the Save Method */
    Assert.assertEquals(0, testQuestion.getId());
    dao.getQuestionRepo().save(testQuestion);
    Assert.assertNotEquals(0, testQuestion.getId());

    /** Check Adding a Choice after the Question was saved & save*/
    Choice choice1 = new Choice("Test - Choice 1");
    testQuestion.addChoice(choice1, false);

    dao.getQuestionRepo().save(testQuestion);

    /* Retrieve the Question and verify the Size of the Array */
    Question retrievedQuestion =         dao.getQuestionRepo().findOne(testQuestion.getId());
    Assert.assertEquals(1, retrievedQuestion.getQuestionChoices().size());

    /** Check Adding a Second Choice and save  */       
    testQuestion.addChoice(new Choice("Test - Choice 2"), false);

    dao.getQuestionRepo().save(testQuestion);

    Question retrievedQuestion2 = dao.getQuestionRepo().findOne(testQuestion.getId());

    Assert.assertEquals(2, retrievedQuestion2.getQuestionChoices().size());

}